File extensions – definition and basic information


File extensions are the integral parts of the files that are on each computer. Often, when working on a computer, we encounter a wide range of files, such as docx, ppt, part, mp3 or rmvb. We realize that they are there – but we often do not know what they are for on our computer.

File extension, also known as the filename extension is a suffix added to the name of a computer file, usually consisting of a number of characters placed after the last dot in the filename, which gives us information about its coding. In other words a file extension is a file format. It allows the operating system (e.g. Windows) to recognize what program it should try to open the file.

In the table below you will find a random selection of popular file extensions.


File extension The full name of the file Category

7Z file extension

7-Zip Compressed File

Compressed Files

ICNS file extension

Mac OS X Icon Resource File

System Files

PPS file extension

PowerPoint Slide Show

Data Files

ZIP file extension

Zipped File

Compressed Files

IBOOKS file extension

Multi-Touch iBook

Data Files

SAV file extension

Saved Game

Game Files

SQL file extension

Structured Query Language Data File

Database Files

GZ file extension

Gnu Zipped Archive

Compressed Files

C file extension

C/C++ Source Code File

Developer Files

GED file extension

GEDCOM Genealogy Data File

Data Files

CFG file extension

Configuration File

Settings Files

MID file extension

MIDI File

Audio Files

3DM file extension

Rhino 3D Model

3D Image Files

MP4 file extension

MPEG-4 Video File

Video Files

CBR file extension

Comic Book RAR Archive

Compressed Files